sylyania Application April 2, Iiig Serial This invention relates to the manufacture of electrical appliances, such as nat-irons, and par ticularly to processes of manufacturing the heating units of such appliances. The invention is s directed speciiically to that class of electrical appliances in. which the electrical element is positioned within a cavity or recess of the appliance. The invention is intended primarily for applicaz tion to electric fiat-irons, in which the heating element is disposed within a cavity or recess in the sole plate of the iron, but the invention is not thus limited and is applicable to other appliances and, in fact, has utility in any instance where the desired purpose may be served. For the. purpose of disclosure, the invention will be described with particular reference to an electric at=iron- It is now common practice in the manufacture ci an electric flat-iron to imbed the heating element in the form of a coil in refractory insulating material within a cavity or recess oi the sole plate above referred to. Heretoiore, the method I, of manufacture has involved the following steps. Some of the refractory insulating cement mois tened with water is rst placed directly in the cavity or recess of the sole plate or casting, after which the heating element is positioned in proper place upon the cement. The heating element is then covered by placing more of the insulating material over it and the previously1 deposited material. Pressure is then applied to the insulating material to compact it in place. .The material is then allowed to dry slowly to eliminate the moisture, and finally the unit is burned or tired to set the cement and remove smoke and fumes from the organic material `usually present in it. In some instances, intermediate drying operations are employed, depending upon the consistency of the insulating material or mixture and the shop procedure oi the manufacturer.

This prior process has certain serious objections, the chief oi which are the multiplicity of steps or operations necessary and the extensive handlirig required. In an article such as an electric fiat-iron, which is plated and bued to a mirror iinish, itis desirable to reduce to, a minimum `the handling of the plated sole plate in which the heating unit is to be imbedded. The imbeddlng material which is commonly employed is usually extremely abrasive, such material usually having a large percentage of fused aluminum oxide, granulated zirconium silicate, ground quartz or the like. If the material comes into contact with the plated .sole plate, there is likely to be produced on the sole plate undesirable scratches which, even though slight, may permanently injure the plate from. the standpoint o appearance and later sale oi the completed article. is apt to happen, and. frequently does happen, the use oi the prior method or process aioye de scribed. f3

The present invention has for its principal che ject, therefore, the provision of a novel process which eliminates the objections of the prior proc ess and which produces a superior product,

A more specific object of the invention is to pro l@ vide a process which involves a minimum number of steps and minimum handling oi the plated soie plate of the article, and which substantially eliminates the possibility oi injury to the plated surfaces of the iron.

The invention may be clearly understood from the following description with reference to thc accompanying drawings, in which Fig. l illustrates the heating element in its initial condition;

Fig. 2 is a perspective view of the preformed heating unit formed by the process;

Fig. 3 is a similar view oi another preformed part;

Fig. i is a perspective View of the heating unit 25 at a later stage in the process;

Fig. S is a perspective view of the sole plate of the flat-iron;

Fig. 6 is a perspective view oi? the cover plate sections;

Fig. 7 is a perspective view ci the sole plate with the preformed unit applied thereto;

Fig. 8 illustrates the iinal step of the process; and

Fig. 9 is a cross-sectional view of the completed product.

In accordance with the preferred form of the process, the heating element is iirst formed as illustrated in Fig. i, and the preformed heating unit shown in Fig. 2 is then formed by molding refractory insulating material around the heating element. This may be done by any of the methods well known in the ceramic molding art. Preferably, the fiati-iron and the heating unit therefor is of the form disclosed and claimed in my copending application, Serial No. 716,874, filed March 22, 1934 and the sole plate of the iron is of the form illustrated in Fig. 5. For this reason, the preformed unit in its initial stage preferably takes the form ci' a stick or bar, as shown in Fig. 2, with spaced notches i which may be readily iormedtduring the preiorming operation and the purpose oi' which will be exn plained presently. The heating element, whose terminals are shown et a, is entirely surround 2li trical characteristics, temperature of omration .of the unit, etc. As the size of the refractory the dimensions of the cavity or recess of the sole 'plate so that it may nt easily therein.

In accordance with the invention, a refractory insulating material is used which will now or extrude in the dry state under applied pressure.

under pressure.

I iind that the addition of talc to the usual mixw ture of. clay and refractory grains assists this flow. The talc content may be as large as 199% of the weight of the grain used. However, a good mixture for practicing my invention consists of 50% fused alumina grain of about 15u size, 25% talc, and 25% refractory clay. f These propor-= tions constitute a little more than enough talc and clay to ll the interspaces between the grains. so that the grain and nller will extrude and dow The proportions ygiven are not the only proportions which may be used, and may vary considerably, depending upon. the elec= grains also determines the mobility thereof, this is a factor to be considered. A suitable organic binder such as is used in making foundry cores may be added to the mix in sumcient quantity to render the preform coherent, and to permit of rough handling.

Following the formation of the preformed unit shown in Fig. 2, using a mobile mixture or material as above described, the unit is allowed to dry by letting it stand for a i'ew days. The unit is then baked at a tempeature of 500 'to 600 F. to remove the organic material usually present and to remove also the smoke and fumes caused thereby. The preformed unit is then re to be placed in the channel or recess of the sole plate. In this state, the unit is sumciently hard to permit of rough handling and to Substantially eliminate the presence of any loose abrasive particles, but it is brittle and capable of being cbled or crushed by relatively high pressure.

Referring to Figs.- i and 5, the preioed unit is bent at the notches above mentioned and formed to the shape shown in Fig. d to adapt it for insertion in the channel or recess l of the sole plate E5, the brittle insulating material break ing at the points of bend. The sharp bending of the unit at the notches l and the consequent breaking of the insulating material exposes the heating element at the corners t, or at least ren ders the insulating material thin at those points, and the vo'ids formed at these corners when the unit is placed in the channel il are lled by means of the preformed triangular pellets or inserts l, such as illustrated in Fig. 3. These rfif in serts may be formed of the same insulating ma terial and in the same manner as the unit itself. The sole plate with the preformed heating unit and inserts l applied thereto is shown in Fig. L After the shaped preformed unit is placed in the recess or channel of the sole plate, the cover plate or cap illustrated in Fig. d is placed over the unit in the channel. The cover plate may comprise two sections 8 as illustrated, shaped in conformity with they channel and formed of sheet metal. The edges of the cover plate sections are bent downwardly so as to engage the side walls of the channel when the sections are expanded therein. ff

The sole plate with the assembled heating unit is then placed in a hydraulic press or like device, as illustrated in Fig. 8, and pressure is applied to the cover plate or cap sufclent to crush or crumble the refractory material and consolidate aoeasoe it in intate contact with the walls of the chan nel or recess. This pressure may be in the neighborhood of 8 tons to the square inch of ere posed cap surface. Very little, if any, displacement oi the heating coil results, so that the neces sary clearance between the channel wall and the coil is maintained. The sole plate'structure is now completed and ready for application oi the usual cover and handle, after which the nat-iron is completed and ready for use. ItV is unnecessary to lire or balie the heating unit after it has been pressed into the sole plate or casting.

The completed sole plate structure is illustrated in Fig. 9. The downwardly-turned edges of the cover plate or cap are expanded outward against the side walls of the channel when the pressure is applied as above described, thus loclr=- -ing the cover plate in place. The cover plate or cap prevents the escape of any of the material oi which the unit is formed around the edges ci the pressing punch or after the unit is in service. It also serves to carry the heat which arises from the heating coil back into the sole plate or casting, particularly by virtue of the contact of its edges or anges with the side walls of the channel. As previously mentioned, this 'structure forms the subject of a copending application.

It will be seen that this process reduces to a minim the handling of the sole plate ln the presence oi the refractory material. IThe said material is brought into association with the sole plate only when the solid preformed heating unit is placed in the channel and pressed to its unal condition. At no time is there any loose moist cement or abrasive material in the vicinity of the sole plate.

The process is simple and involves a minimum number of steps or operations and at the same vtime it results in an improved article. The iincommodating the same need 'not take the specic forms illustrated, the invention contemplating broadly the formation of the preformed unit and its later application to the sole plate. More-vi over, theprccess may be modied as to its de= I claim:

l. In the manufacture of electric appliances, such as nat-drone, the method which comprises initially preforming an electrical heating unit by molding about a current conductor a body of mobile refractory insulating material shaped to rit in a cavity or recess of the appliance thus forming a self-supporting unit comprising only the insulating material and the embedded conductor, placing the preformed unit in the said cavity or recess with said insulating material contacting the walls of said cavity, and subjecting the unit to pressure sumcient to crush and consolidate the unit in its cavity.

' 2. ln the manufacture of electric appliances, such as nat-irons, the method which comprises initially prefog an electrical heating unit by molding about a current conductor a. body of mobile refractory insulating'material shaped to t in a cavity or recess of the appliance thus forming a self-supporting unit comprising only the insulating material and the embedded conductor, placing the preformed unit in the said cavity or recess with said insulating material contacting the walls of said cavity, covering the unit with a sheet metal cap to seal the said cavity or recess, and applying pressure to said cap suillcient to crush and consolidate the unit in the cavity and to lock the cap therein.

3. In the manufacture of electric appliances. such as fiat-irons, the method which comprises initially preforming an electrical heating unit by molding completely about a current conductor a body of mobile refractory insulating material shaped to fit in a cavity or recess of the appliance thus forming a self-supporting unit comprising only the insulating material and the embedded conductor, placing the preformed unit in the said cavityor recess with said insulating material contacting nie wus of said. cavity, covering the unit with a sheet metal cap having turned-down edges to seal the said cavity or recess, and applying lpressure to said cap sumcient to crush and consolidate the unit in the cavity and to lock the cap therein.

4. In the manufacture of electric appliances, such as flat-irons, the method which comprises initially preforming an electrical heating unit by molding completely about a current conductor a body of mobile refractory insulating talc-containing material shaped to ilt in a cavity or recess of the appliance thus forming a self-supporting unit comprising only the insulating material and the embedded conductor, placing the preformed unit in the said cavity or recess with said insulating material contacting the Walls of said cavity, and subjecting the unit to pressure sufilcient to crush and consolidate the unit in its cavity.

5. In the manufacture of electric appliances, such as flat-irons, the method which comprises initially preforming an electrical heating unit by molding completely about a current conductor a body of mobile refractory insulating material shaped to nt in a cavity or recess of the appliance thus forming a self-supporting unit comprising only the insulating material and the embedded conductor, said material containing an extrudable filler capable of flowing under pressure when dry, placing the preformed unit in the .said cavity or recess with said insulating material contacting the Walls of .said cavity, and subjecting the unit to pressure suiuclent to crush and consolidate tile unit in its cavity.

6. In the manufacture of electric appliances, such as flat-irons, the method which comprises initially preformed an. electrical heating unit by molding completely about a current conductor a body of mobile refractory insulating material shaped to iit in a cavity or recess of the appliance thus forming a selfnsupporting unit comprising l its cavity.

only the insulating material and the embedded conductor, drying the preformed unit, placing the preformed unit in the said cavity or recess with said insulating material contacting the walls of said cavity, and subjecting the unit to pressure suillcient to crush and consolidate the unit in its cavity.

7. In the manufacture of electric appliances, such as fiat-irons, the method which comprises initially preforming an electrical heating unit by molding completely about a current conductor a body of mobile refractory insulating material shaped to fit in a cavity or recess of the appliance thus forming a self-supporting unit comprising only the insulating material and the embedded conductor, baking the preformed unit, placing the preformed unit in the said cavity or recess with said insulating material contacting the walls of said cavity, and subjecting the unit to pressure sufficient to crush and consolidate the unit in its cavity.

8. In the manufacture of electric appliances, such as fiat-irons, the method which comprises initially preforming an electrical heating unit by molding completely about a current conductor a body of mobile refractory insulating material shaped to fit in a cavity or recess of the appliance thus forming a self-supporting unit comprising only the insulating material and the embedded conductor, drying the preformed unit, baking the unit, placing the preformed unit in the said cavity or recess with said insulating material contacting the walls of said cavity, and subjecting the unit to pressure sumclent to crush and consolidate the unit in its cavity.

9. In the manufacture of electric appliances, such as flat-irons, the method which comprises preforming a stick-like electrical unit by molding about a current conductor a body of mobile refractory insulating material dimensioned to flt in a cavity or recess of the appliance and provided with spaced notches, bending said unit at the said notches to shape it in conformity with said cavity or recess, placing the shaped unit in the said cavity or recess together with inserts at the bent notched portions of the unit, and subjecting the unit to pressure sumcient to crush and consolidate the unit in its cavity.

lit-In the manufacture of electric appliances, such as flat-irons, the method which comprises preforming a stick-'like electrical unit by molding about a current conductor a body of mobile re 'Jessen w. MYERS.